12mm front trim ring - need to buy, where?

Anyone know where I can get the front trim ring for the Oly 12mm? I tried Google, but I'm not sure what the correct terminology is. It's the ring on the front of the lens that the Oly metal hood would clamp on to. I know it unscrews, though I'm not entirely sure why it does. Anyway, I'm looking for that part. Anyone have a link or anything? Thanks.

The 12mm, and the other metal bodied lenses (75mm F/1.8 & 17mm F/1.8) don't have trim rings or at least none came with mine. Not all of the plastic bodied lenses have trim rings either,

If you want to check whether or not there is a trim ring for a particular lens then the simplest way I know to be sure is to look at the manual for the lens on the Olympus site. There's a diagrammatic view of the lens in the manual with every feature noted. If there is a trim ring then it will appear in the diagram.

Oh, crap. I'm a complete idiot. I just actually looked at the lens which I hadn't done before. The dude actually sent me a 45mm instead of a 12mm. Can't believe I missed that. Well. Off to file a claim.